Oengus, [78], [81], [86], [146], [387].

Oghams, [75].

Ogma, [54], [74-75].

Ogmíos, [25], [75].

Oilill Olom, [70].

Oisin, [142], [150-151], [152] f., [222], [364], [379], [387].

Omens, [247] f.

Oracles, [179], [196].

Oran, [238].

Orbis alius, [340].